Do you mean appending a string "1", "S" or "single" to a line in a Grub boot configuration which reads as the string "boot"?
According to GRUB documentation, the boot command takes no arguments. I'd be surprised to hear that grub didn't complain about this -- if I have understood you correctly -- but in that case, then, none of them should have any particular effect.
Are you referring to some argument to the kernel? http://www.mjmwired.net/kernel/Docum...parameters.txt